Subadiabatic combustion of premixed gas in ceramic foam burner

Abstract

During the combustion of low-concentration coal mine methane in a porous medium, subadiabatic combustion will occur with the upstream propagation of combustion waves. The lower concentration limit of methane combustion can be broadened, when the porous medium skeleton is preheated by the upstream propagation of combustion waves. In this study, an experimental apparatus of porous medium combustion was built and used to validate a numerical model. Then numerical tests were conducted to characterize the upstream propagation of combustion waves, and investigate the effects of many factors (e.g. methane working conditions, heat loss through walls, and dispersion effect) on the propagation. Results show that the upstream propagation of combustion waves is kept at an even velocity. During the propagation, the combustion products temperature at the burner outlet gradually decreases, while the peak temperature is unchanged. With the increase of methane concentration, the upstream propagation velocity of combustion waves and the peak temperature both increase. As the inlet gas velocity is increased, the upstream propagation velocity decreases but the peak temperature raises. As the heat loss through walls is increased, the upstream propagation velocity and the peak temperature both decrease. The CO emission quantity gradually decreases during the upstream propagation of combustion waves. With the increase of inlet velocity and heat loss through walls, the CO emission quantity within the same propagation period gradually increases. The NO emission quantity first increases slowly and then stabilizes during the upstream propagation of combustion waves. Moreover, with the increase of inlet velocity and decrease of heat loss through walls, the NO emission quantity within the same propagation period increases.